Java通過URL 從web服務端獲取數據

1、Java 通過HttpURLConnection Post方式提交json，並從服務端返回json數據

package Demo.Test;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class App {
    
    public static void readParse(String urlPath,String str) throws Exception {
        System.out.println(str);
        
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] data = new byte[1024];
        int len = 0;

        URL url = new URL(urlPath);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        // 設置傳遞方式
        conn.setRequestMethod("POST");
        //代理
        conn.addRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
        
        conn.setRequestProperty("Content-Type", "application/json");
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 設置不用緩存
        conn.setUseCaches(false);
        //權限
        conn.setRequestProperty("Authorization", " Bearer fc58be57c46b32f9a2c32e5393684ac0");
        
         // 開始連接請求
        conn.connect();
        OutputStream  out = conn.getOutputStream();     
        // 寫入請求的字符串
        out.write((str).getBytes());
        out.flush();
        out.close();
        
        // 請求返回的狀態
        if (conn.getResponseCode() == 200) {
            System.out.println("連接成功");
            // 請求返回的數據
            InputStream in = conn.getInputStream();
            String a = null;
            try {
                byte[] data1 = new byte[in.available()];
                in.read(data1);
                // 轉成字符串
                a = new String(data1);
                System.out.println(a);
            } catch (Exception e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        } else {
            System.out.println(conn.getResponseCode()+":no++");
        }

    }
    public static void main(String[] args) throws Exception {//地址
        String url = "http://...";
        //查詢參數
        String str = "{\"ids\":[15410,15402]}";
        readParse(url,str);
    }
}

 注：如果你的代碼報錯：java.io.IOException: Server returned HTTP response code: 403 for URL https://...... 訪問被拒絕

　　你需要在代碼中加入請求頭信息

// 設置允許輸出
conn.setDoOutput(true);

conn.setDoInput(true);

// 設置不用緩存
conn.setUseCaches(false);
// 設置傳遞方式
conn.setRequestMethod("POST");
// 設置維持長連接
conn.setRequestProperty("Connection", "Keep-Alive");
// 設置文件字符集:
conn.setRequestProperty("Charset", "UTF-8");

// 設置文件長度
conn.setRequestProperty("Content-Length", String.valueOf(data.length));

// 設置文件類型:
conn.setRequestProperty("contentType", "application/json");
//代理
conn.addRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
//權限---需要根據自己情況進行修改
conn.setRequestProperty("Authorization", " Bearer fc58be57c46b32f9a2c32e5393684ac0");

 GET方式訪問weatherAPI接口實例

import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

public class WeatherAPI {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        WeatherAPI.json("北京");
        //3秒后繼續執行
        Thread.sleep(3000); 
        WeatherAPI.xml("東京");
    }
    public static void json(String strcity) throws Exception{
        //參數url化
        String city = java.net.URLEncoder.encode(strcity, "utf-8");
        //拼地址
        String apiUrl = String.format("https://www.sojson.com/open/api/weather/json.shtml?city=%s",city);
        //開始請求
        URL url= new URL(apiUrl);
        URLConnection open = url.openConnection();
        InputStream input = open.getInputStream();
        //這里轉換為String，帶上包名，怕你們引錯包
        String result = org.apache.commons.io.IOUtils.toString(input,"utf-8");
        //輸出
        System.out.println(result);
    }

    public static void xml(String strcity) throws Exception{
        //參數url化
        String city = java.net.URLEncoder.encode(strcity, "utf-8");
        //拼地址
        String apiUrl = String.format("https://www.sojson.com/open/api/weather/xml.shtml?city=%s",city);
        //開始請求
        URL url= new URL(apiUrl);
        URLConnection open = url.openConnection();
        InputStream input = open.getInputStream();
        //這里轉換為String，帶上包名，怕你們引錯包
        String result = org.apache.commons.io.IOUtils.toString(input,"utf-8");
        //輸出
        System.out.println(result);
    }
}

 僅做筆記！如果疑問望告知。